Process of cyaniding.



H. R. LAYNG.

PROCESS OF CYANIDING.

APPLICATION FILED 050.29, 1914.

i i i: km" 1 i 2 l I i \VYDXESSES: mvEN'rOR UN 3" lEl) HAIUAI R. LAEZNG, F SENECA, UALIE'ORNIA.

ncense.

Application filed December 2a. 191 Serial 1m. scans.

To all whom it may concern.

' Be itknown that I, Hamil ll. Invite, a citizen of the l nitetl States, residing at Seneca, in.the county of Plumas and State of California, have invented new and useful and the like' ducting the The chief objectsof this process are to improve on present methods cyanidation and to lessen the cost of cyanidation.

Other objects are to provide a'cheap, siniple and effective means to regenerate cyanid fi'oni'solutions or other matter resulting from the treatment of ores by cyanitjiation; to provide a cheap, simple; and eiiective means for precipitating values from. solutions, and to render used ori' oul cyanid so-- lutions more efficient for extraction purposes, a

The drawing shows the arrangement of the devices in a simple manner for conpr'ocess on an intermittent scale in which- A is a suitable sealed device in which the solutions are treated; 1 an inlet for solution; 30

5 an outlet for treated solution; 6 a dis charge for precipitate; 7 a feed port and in let for airy'S an inlet for chemicals; C a re tort: D stock vats for chemicals; 9 an outlet from the retort; E a nitric absorption device; 10 a conduit; F a cyanid absorption device; G a pump; 11 heating coils; 12 an outlet for nitric acid; 13 an inlet for water; 14 an inlet for chemicals; 15 an outlet for cyanid; 16 a discharge from the pump; and

17 and 18 check valves. I

I have round in treating many ores by cyanidation that much cyanid is consumed.

through the formation oi complex cyanogen compounds such as sultlocyanids and double salts thereof with the metal cyanids; silver, copper "and other metals entering the solution as a sulfocyanid dissolved in cyanid, as expressed by the following equations: 2AgS+4 KCN+H O+O: I

j 2AgCNS.KCN+QKOI-l ZCuS-l-SKCN-tilllfl): 1

- Cu (CNS) .fiKUU-l-QKOH+H The above equations iSllQ\\' that one halt of the cyanid consumed by silver is consumed through the formation of suli'ocv,

anid. Coinpi'uiiids like C11 (CKS) 2 when contained in a cyanid solution seriously reduce the solvent efficiency of cyanid solutions and for that reason they are the cause of low extractions of gold and silver from ores by cyanidation. Relatively large amounts of free sul iocyanid, such as KCLTS, also have a tendency to reduce the extractive elliciency of c anid.

The methods of precipitation in common use, namely zinc or aluminum methods, do not completely precipitate such compounds as Cugfllfi'a from cyanid solutions and they cause free sulfocyanid to be formed, may be shown by the following equation: AgCNSlQCN-l-MQCN-l-Zn+H O in describing this process i Wish it understood that I do not limit the process to precipitation as other precipitation processes may be used in conjunction with it; that the process may be used in conjunction with any other cyanid processes; and that the process is of such a nature as will allow it to be modified and: used in manycforms without its being otherwise changed in nature or pur-.

pose. 1

in conducting the process the solution re- ,sulting from the treatment of the ore is treated in a sealed device A, or any other suitable device, which will prevent the escape of HUN, with any suitable chemical such as acids which will cause the suite- T' compounds to be precipitated from the St'illllllOIi. F or eaainplei- CLI CNS OZ ICN+EL-LSO V: Cu CN -l6HCN+3K SO 2Ag( llSliCN-t-ELSOQ: QAgCNS-l-EZHCN-l-K,

It may be herein mentioned that in cases wherein thesilveris not all in solution as a sulfocyanid but as siin le cyanid dissolved incyanid, and wherein t ie solution contains free sulfocyanid, the acidification of such a solution will. cause the transposition of the 'silvercyanid to silver sultocyanid. For ex ample 2 i KAg'(CN)- +KCNS+H SO *In case the solution contains free suite-- cyanid this may be separated from the solu tion, if desired, by precipitation as an in? soluble compound by means of reducing I the cyanogen which would otherwise have aid in the separation.

been contained in the silver cyanid. Heat maybe applied in the above steps of the processto facilitate the precipitation and The precipitate so formedzgis separated from the solution by settlihg'or filtering, or a combination of both procedhres, and is treated in a suitable retort C with an oxidizing agent, such as sno haNO or the hke, preferably in the presence of sulfuric or other sultable acid, With the aid of heat. This treatment causes the'sulfur of the CNS to be oxidized to sulfate and the cyanogen to combine with hydrogen to form hydrocyanic acid according to the following equations: KCNS+2NalYQ +2H SO While the above reactions are occurring in the retort C air is admitted either to the retort or at someother convenient place to supply the oxygen necessary to oxidize the nitrogen gases to nitric acid or for other purposes, such as to facilitate the conveyance of the gases. The gases from the retort are conveyed to any suitable absorption device E containing water, wherein the reactions between the oxygen of the air and the nitrogen gases are completed and wherein the nitric acid is retained and from which it maybe drawn for use as desired. The gases containing the HCN are then conveyed to any suitable absorption device F containing any suitable absorption material, forexample CaO or l uOH which will combine with the hydrocyanic acid to form cyanid which will remain in the de vice and which can be drawn from the device and used as desired.

The residue in the retort, after the re moval of as much of the HCN or nitrate by heat or mechanical means as will prove profitable, may be treated as desired to recover the values. This residue usually contains copper sulfate which may be'separated from the other compounds by any suitable means and used in the presence of reducing agent, such as S6 to precipitate free sulfocyanid from the acidified cyanid solution of the first step of this process, or it may be treated with salt and a reducing agent so as to form cuprous chlorid which may also be used for precipitating free sulfocyanid and the like from the acidified cyanid solution.

- such simple cyanids more eiiicient.

- junction with the nitrate in cases wherein some simple cyanids like i gCN are containcd in the precipitate produced in the first step of this process for the purpose of rendering the regeneration of cyanid from 1 further wish it understood that the process maybe conducted either wholly or inpart as either an intermittent a continuous process or a combination of both.

The strength of the and nitrate used in the treatment of the precipitate y according to the nature of the precipitate;

. so also does the manner of applying them as well as does the heat. Thus silver sulfocyanid will glve good yields of cyanid with fairly strong acids,-while' cuprous sulfocyanid requires weaker acids in order to obtain a good yield. The strength oi -the acid and the temperature or" the charge, together with the manner of procedure which will have to be allowed on precipitates from different solutions, will vary With the nature of the solution and can be determined by simple laboratory tests or experiments upon the particular precipitate. The acidified cyanid solution from which the precipitate has been removed may be treated in a sealed device B with an alkali to regenerate cyauid from its contained hydrocyanic acid which was liberated by the first steps of this process and then used as desired, or it may be otherwise treated as desired.

It has been shown by the foregoing that the chemical treatment of causes the double cyanogen compounds to break up, forming a. gaseous cyanogen com pound, viz. HCN, and an insoluble cyanogen compound which, when treated with suit able chemicals in a suitable device, resolves in the formation of available cyanid and that the chemical used in treating the insoluble cyanogen compound is also regenerated to an available form. Thus it is eyident that the process is economical.

Numerous tests with this process have shown that a regeneration of over oi the cyanid consumed in forming sulfocyanid at a cost not exceeding 4c. per pound of cyanid in terms of KCN regenerated can be obtained; also that about of the nitrate used to regenerate cyanid from sulfocyanid is regenerated and recovered in an available form. The tests also show that all of the cyanid used in holding the insoluble cyanogcn compounds, like CIIJCNSL in solution is regenerated at a good profit. They also show that all. of the metals, like copper, are precipitated and that the solution after having been treated by this process nave much more extraction ethciency than had before treatment.

the solution they inc

into by any 'suitabie means to recover the chemicals, and treaiing the resui zing gases by any suitabie means no regenerate oyanid, substantially as describe :9. A process for regenerating cyanid from a yanid solution containing compounds of ziimibie metals which comprises treating the soiu'iiozi with an acid to aprecipitsta cyanogen compounds of she metals and form a solution containing hydrooyanic acid, separating the precipitate and treating ii with a mixture comprising. an oxidizing agent and. capable of converting cyanid into bydroeyanis acid to decompose any metal cyand suifooyanid presentinto a difi'er ent metal compound and. m gaseous inixi'ure contziiiilng hydrocynnic acid, and treating snic gaseous mixture and said solution containing hydroeyai ic acid to regenemfie available cyanid, substantially as describech In testimony whereof I have hereunto set my hand in .the presence. of two subscribing witnesses HARAI R. LAYNG'.

iVitnesses:

JOHN H. himizmo, FRANCES V. COLE. 

